Scalable dynamic range analog-to-digital converter system

ABSTRACT

A scalable dynamic range analog-to-digital converter. In one instance, a method of scaling a dynamic range of an analog-to-digital converter is provided. The method includes operating the analog-to-digital converter at a first dynamic range. The method also includes receiving a radio frequency signal and detecting an on-channel signal level of the radio frequency signal. The method also includes when the on-channel signal level is above an on-channel threshold, operating the analog-to-digital converter at a second dynamic range. The method also includes when the on-channel signal level is below the on-channel threshold, operating the analog-to-digital converter at the first dynamic range.

BACKGROUND

Mobile communication devices such as smart telephones, land mobileradios, and the like may need high dynamic range analog-to-digitalconverters to receive weak signals when strong interference signals arepresent. Generally, high dynamic range analog-to-digital convertersrequire large amounts of power. As a consequence, this type ofanalog-to-digital converter affects battery life and strong signal spurmitigation of the mobile communication devices.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, together with the detailed description below, are incorporated inand form part of the specification, and serve to further illustrateembodiments of concepts that include the claimed subject matter, andexplain various principles and advantages of those embodiments.

FIG. 1 is a diagram of a mobile communications device in accordance withsome embodiments.

FIG. 2 is a simplified block diagram of a portion of a transceiver ofthe mobile communications device of FIG. 1 in accordance with someembodiments.

FIG. 3 is a simplified diagram of a sigma-delta modulator of theanalog-to-digital converter of FIG. 2 in accordance with someembodiments.

FIG. 4 is a flowchart of a method of scaling a dynamic range of theanalog-to-digital converter of FIG. 2 in accordance with someembodiments.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of various embodiments.

The apparatus and method components have been represented whereappropriate by conventional symbols in the drawings, showing only thosespecific details that are pertinent to understanding embodiments and soas not to obscure the disclosure with details that will be readilyapparent to those of ordinary skill in the art having the benefit of thedescription herein.

DETAILED DESCRIPTION OF THE INVENTION

Analog-to-digital converters may include switched capacitor sigma-deltamodulators that convert analog signals received at an antenna of themobile communications device to digital signals. The capacitors inswitched capacitor sigma-delta modulators are often a source of thermalnoise, which is often represented or modelled using the relationshipkT/C, where k is Boltzmann's constant in joules per Kelvin, T isabsolute temperature, and C is the capacitance in farads). In order toachieve high dynamic range and low switching noise, sigma-deltamodulators often incorporate large capacitors. To charge and dischargethese large capacitors at a high clock rate, high speed clocks andoperational amplifiers that require higher current are used. As aconsequence, high dynamic range analog-to-digital converters reducebattery life.

However, high dynamic range is not always necessary. Advancements innetworks (for example, an increased number of base stations) hasimproved network coverage and decreased the likelihood of receiving aweak signal. As a consequence, analog-to-digital converters need notoperate at high-dynamic range when the mobile communications devicereceives relatively strong signals.

One embodiment provides a scalable dynamic range analog-to-digitalconverter including a switched capacitor sigma-delta modulator. Thesigma-delta modulator includes a first capacitor having a firstcapacitance value and a second capacitor having a second capacitancevalue. The analog-to-digital converter also includes a receiverelectronic processor that controls a switching operation of the switchedcapacitor sigma-delta modulator and receives an on-channel signal levelof an on-channel signal. The receiver electronic processor switches inthe first capacitor when the on-channel signal level is below anon-channel threshold. The receiver electronic processor switches in thesecond capacitor when the on-channel signal level is above theon-channel threshold.

Another embodiment provides a mobile communications device including aninternal antenna receiving a radio frequency (RF) signal and anon-channel detector coupled to the internal antenna. The on-channeldetector is configured to detect an on-channel signal level of the radiofrequency signal. The mobile communications device also includes ananalog-to-digital converter coupled to the internal antenna to convertthe radio frequency signal to a digital signal and includes a switchedcapacitor sigma-delta modulator. The sigma-delta modulator includes afirst capacitor having a first capacitance value and a second capacitorhaving a second capacitance value. The mobile communications device alsoincludes a receiver electronic processor that controls a switchingoperation of the switched capacitor sigma-delta modulator, wherein thereceiver electronic processor switches in the first capacitor when theon-channel signal level is below an on-channel threshold. The receiverelectronic processor switches in the second capacitor when theon-channel signal level is above the on-channel threshold.

Another embodiment provides a method of scaling a dynamic range of ananalog-to-digital converter. The method includes operating theanalog-to-digital converter at a first dynamic range. The method alsoincludes receiving a radio frequency signal and detecting an on-channelsignal level of the radio frequency signal. The method also includeswhen the on-channel signal level is above an on-channel threshold,operating the analog-to-digital converter at a second dynamic range. Themethod also includes when the on-channel signal level is below theon-channel threshold, operating the analog-to-digital converter at thefirst dynamic range.

FIG. 1 is a diagram of one embodiment of a mobile communications device100. The mobile communications device 100 may be a mobile, a portable ora handset device including, for example, a two-way radio, a vehiclemounted two-way radio, a smart telephone, a tablet computer, or thelike. In the example illustrated, the mobile communications device 100includes an electronic processor 110, a memory 120, a transceiver 130,and an antenna 140. The electronic processor 110, the memory 120, andthe transceiver 130 communicate over one or more control and/or databuses (for example, a communication bus 150). FIG. 1 illustrates onlyone exemplary embodiment of a mobile communications device 100. Themobile communications device 100 may include more or fewer componentsand may perform functions other than those explicitly described herein.

In some embodiments, the electronic processor 110 is implemented as amicroprocessor with separate memory, such as the memory 120. In otherembodiments, the electronic processor 110 may be implemented as amicrocontroller (with memory 120 on the same chip). In otherembodiments, the electronic processor 110 may be implemented usingmultiple processors. In addition, the electronic processor 110 may beimplemented partially or entirely as, for example, a field programmablegate array (FPGA), and application specific integrated circuit (ASIC),and the like and the memory 120 may not be needed or be modifiedaccordingly. In the example illustrated, the memory 120 includesnon-transitory, computer-readable memory that stores instructions thatare received and executed by the electronic processor 110 to carry outthe functionality of the mobile communications device 100 describedherein. The memory 120 may include, for example, a program storage areaand a data storage area. The program storage area and the data storagearea may include combinations of different types of memory, such asread-only memory and random-access memory.

The transceiver 130 enables wireless communication from the mobilecommunications device 100 to, for example, other mobile communicationsdevices 100, a call controller, or other electronic devices. Thetransceiver 130 is coupled to an antenna 140 to receive and sendcommunication signals. The antenna 140 may be, for example, an internalantenna of the mobile communications device 100 or an external antennaconnected to the mobile communications device 100. The transceiver 130communicates through the antenna 140 to at least one of a plurality ofwireless radio frequency (RF) channels of certain bandwidth and havingprotocol compliance so as to transmit and/or receive on-channelcommunication signals as may be modulated onto a radio frequency carriersignal. The transceiver 130 includes an analog-to-digital converter 160in a receiver portion of the transceiver 130 to convert received analogsignals from the antenna 140 to digital signals to be transmitted to thecomponents of the mobile communications device 100. The transceiver 130also includes a digital-to-analog converter 170 in a transmitter portionof the transceiver 130 to convert digital signals received from thecomponents of the mobile communications device 100 to analog signals tobe transmitted from the antenna 140. In other embodiments, rather thanthe transceiver 130, the mobile communications device 100 may includeseparate transmitting and receiving components, for example, atransmitter and a receiver.

FIG. 2 is a simplified block diagram of one embodiment of a receiverportion 200 of the transceiver 130 incorporating a scalable dynamicrange analog-to-digital converter 160. The analog-to-digital converter160 receives analog radio frequency (RF) signals from the antenna 140and converts the analog signal to digital signals. In the exampleillustrated, the receiver portion 200 includes a receiver front end 202and a receiver intermediate frequency section 204. The receiver frontend 202 may be partly provided in the antenna 140 and receives the radiofrequency signals from a base station. The receiver front end 202includes a filter 206, a low-noise amplifier 208, a quadrature splitter210, and a mixer 212.

The antenna 140 receives the radio frequency signals and filters andconditions them with the filter 206 and the low-noise amplifier 208. Thefiltered radio frequency signals are then provided to the quadraturesplitter 210, which splits the filtered radio frequency signals intoin-phase and quadrature components by means of, for example, quadraturemixers. The in-phase and the quadrature components are then provided tothe receiver intermediate frequency section 204.

The receiver intermediate frequency section 204 includes a firstamplifier 214, an off-channel detector 216, a first low-pass filter 218,a second amplifier 220, a second low-pass filter 222, a third amplifier224, a sigma-delta modulator 226 including an integrator 228, anon-channel detector 230, a RF signal scaling and spur estimator 232, asample rate and bandwidth controller 234, an automatic gain controlthreshold set block 236, and an automatic gain control state machine238. In some embodiments, the sigma-delta modulator 226 and theintegrator 228 are part of the analog-to-digital converter 160. In someembodiments, the analog-to-digital converter 160 may also additionallyinclude the second low-pass filter 222, the third amplifier 224, the RFsignal scaling and spur estimator 232, the sample rate and bandwidthcontroller 234, or the automatic gain control threshold set block 236.

The received radio frequency signal may include both an on-channelsignal and an off-channel signal. The on-channel signal is the desiredsignal of the mobile communications device 100, for example, signalwithin the operating frequency or band of the mobile communicationsdevice 100 and directed to the mobile communications device 100. Theoff-channel signal may be out-of-band or undesired signals or signalsnot directed to the mobile communications device 100 that may arise froman interference or noise source.

The in-phase and quadrature components are provided to the off-channeldetector 216 after passing through the mixer 212 and the first amplifier214 (for example, a transimpedance amplifier). The off-channel detector216 may detect the power level, strength, quality, range, and the likeof the off-channel signal (or noise) (for example, off-channel signalprofile). The off-channel detector 216 provides the off-channel signalprofile information to the RF signal scaling and spur estimator 232.

The in-phase and quadrature components are then provided to thesigma-delta modulator 226 after passing through the first low-passfilter 218 (for example, a one-pole low-pass filter), the secondamplifier 220, the second low-pass filter 222 (for example, a two-polefilter), and the third amplifier 224. The sigma-delta modulator 226converts the in-phase and quadrature components into digital signalsthat can be used by the components of the mobile communications device100. Although the analog-to-digital converter 160 is shown including asingle sigma-delta modulator 226, the sigma-delta modulator 226 may beimplemented as a plurality of sigma-delta modulators 226 as may beneeded to appropriately sample the on-channel signal. For example, theanalog-to-digital converter 160 may include two sigma-delta convertersto sample the in-phase component and the quadrature componentrespectively. The output of the plurality of sigma-delta modulators 226may be combined to provide a sample representation of the on-channelsignal to the on-channel detector 230 and other components of the mobilecommunications device 100.

The on-channel detector 230 is connected to the sigma-delta modulator226 to detect the power level, strength, quality or the like of theon-channel signal (for example, on-channel signal level). The on-channeldetector 230 provides the on-channel signal level information to the RFsignal scaling and spur estimator 232 and the automatic gain controlthreshold set block 236.

The RF signal scaling and spur estimator 232 receives the on-channelsignal level and the off-channel signal profile and provides scaledthresholds (for example, on-channel thresholds) to the automatic gaincontrol threshold set block 236 and thereby to the automatic gaincontrol state machine 238. The RF signal scaling and spur estimator 232may set the scaled thresholds based on the on-channel signal level andthe off-channel signal profile. The scaled thresholds may includevarious step sizes and levels based on the received signals. Forexample, the RF signal scaling and spur estimator 232 may set a higherstep size when the RF signal scaling and spur estimator 232 detects thatthere is high level of noise based on the off-channel signal profile andmay set a lower step size when the RF signal scaling and spur estimator232 detects that there is a low level of noise based on the off-channelsignal profile.

The automatic gain control threshold set block 236 receives theon-channel signal level and the scaled threshold and may determinewhether the on-channel signal level is above or below the scaledthreshold. In some embodiments, the automatic gain control threshold setblock 236 may be controlled by the RF signal scaling and spur estimator232 or may be implemented in the RF signal scaling and spur estimator232.

The sample rate and bandwidth controller 234 controls the sample rate atwhich the sigma-delta controller samples the on-channel signal (forexample, the in-phase and quadrature components) based on the on-channelsignal level and threshold information received from the RF signalscaling and spur estimator 232. In addition, the sample rate andbandwidth controller 234 also controls the dynamic range of thesigma-delta modulator 226 based on the on-channel signal level andthreshold information received from the RF signal scaling and spurestimator 232. The sample rate and bandwidth controller 234 alsocontrols the first low-pass filter 218 and the second low-pass filter 22based on the information received from the RF signal scaling and spurestimator 232. In some embodiments, the sample rate and bandwidthcontroller 234 receives control signals from the automatic gain controlstate machine 238 or the RF signal scaling and spur estimator 232 tochange the sample rate and dynamic range of the sigma-delta modulator226. In some embodiments, the sample rate and bandwidth controller 234is implemented in the RF signal scaling and spur estimator 232.

The automatic gain control state machine 238 receives the on-channelsignal level and off-channel signal profile information andautomatically sets the gain of the antenna 140. The automatic gaincontrol state machine 238 provides automatic gain control attenuationcontrol voltage to the quadrature splitter 210. The quadrature splitter210 splits the received radio frequency signal into in-phase andquadrature components based on the control voltage received from theautomatic gain control state machine 238. In some embodiments, theautomatic gain control state machine 238 is configured to set thedynamic range of the sigma-delta modulator 226.

The automatic gain control state machine 238, and accordingly thereceiver portion 200, may include, for example, n states correspondingto n−1 on-channel thresholds. The automatic gain control state machine238, therefore, adjusts the gain of the receiver portion 200 based onthe on-channel signal level. Each of then states may have differentupdate rates, or threshold step sizes. As described above, the RF signalscaling and spur estimator 232 sets the n−1 thresholds of the receiverportion 200 based on the on-channel signal profile and off-channelsignal profile. For simplicity, the methods in the present disclosureare described with respect to two states (for example, high dynamicrange and low dynamic range) and including a single on-channelthreshold. However, it will be apparent that the receiver portion 200,the automatic gain control state machine 238, and the analog-to-digitalconverter 160 may include different number of states and thresholds.

In some embodiments, the RF signal scaling and spur estimator 232, thesample rate and bandwidth controller 234, and/or the automatic gaincontrol threshold set block 236 are functional blocks that areimplemented on a task-specific state machine, a separate processor (forexample, an application specific integrated circuit) of the receiverportion 200, the electronic processor 110, or the like. Therefore, thefunctional blocks of the RF signal scaling and spur estimator 232, thesample rate and bandwidth controller 234, and/or the automatic gaincontrol threshold set block 236 are together referred to as a receiverelectronic processor. As described above with respect to the electronicprocessor 110, the receiver electronic processor may be implemented witha separate memory or a memory (for example, a receiver memory) includedon the same chip. The receiver memory may store a decision matrix, alook-up table, or the like that allows the RF signal scaling and spurestimator 232 to set the on-channel thresholds based on the on-channelsignal profile and the off-channel signal profile.

FIG. 2 illustrates only one exemplary embodiment of theanalog-to-digital converter 160. The analog-to-digital converter 160 mayinclude more of fewer components than illustrated and may performadditional functions other than those described herein.

FIG. 3 is a simplified diagram of one embodiment of an integrator 228 ofthe sigma-delta modulator 226. In the example illustrated, thesigma-delta modulator 226 is a switched capacitor sigma-delta modulatorand includes a first input capacitor 310, a second input capacitor 320,an integrating amplifier 330, a first feedback capacitor 340, and asecond feedback capacitor 350. The integrating amplifier 330, the firstfeedback capacitor 340, and the second feedback capacitor 350 may formthe integrator 228 of the analog-to-digital converter 160. In addition,the first input capacitor 310 and the first feedback capacitor 340 maytogether or individually be referred to as the first capacitor and thesecond input capacitor 320 and the second feedback capacitor 350 maytogether or individually be referred to as the second capacitor. FIG. 3illustrates only one exemplary partial embodiment of a first stage ofthe sigma-delta modulator 226. The sigma-delta modulator 226 may includemore of fewer components than illustrated and may perform additionalfunctions other than those described herein. For example, thesigma-delta modulator 226 may include additional input capacitors andfeedback capacitors to correspond to the multiple states of thereceiver. These multiple capacitors may be selected based on therequirements of the receiver portion 200.

Analog input V_(AI) is provided to sigma-delta modulator 226 from theantenna 140. The analog input V_(AI) is provided to the first inputcapacitor 310 and the second input capacitor 320 through switches S11and S21 respectively. Outputs of the first input capacitor 310 and thesecond input capacitor 320 are provided to the integrating amplifier 330through switches S12 and S22 respectively. The first input capacitor 310samples the analog input V_(AI) when the switch S11 is closed anddischarges onto the integrating amplifier 330 when the switch S12 isclosed. Similarly, the second input capacitor 320 samples the analoginput V_(AI) when the switch S21 is closed and discharges onto theintegrating amplifier 330 when the switch S22 is closed.

The integrating amplifier 330 integrates the sampled input V_(AI) fromeither the first input capacitor 310 or the second input capacitor 320and outputs a digital signal VDO. The first feedback capacitor 340 maybe connected between the input and the output of the integratingamplifier 330 by switches S31 and S32. Similarly, the second feedbackcapacitor 350 may be connected between the input and the output of theintegrating amplifier 330 by switches S41 and S42.

The first input capacitor 310 and the first feedback capacitor 340 mayhave a higher capacitance value (for example, first capacitance value)than the capacitance value (for example, second capacitance value) ofthe second input capacitor 320 and the second feedback capacitor 350.The sigma-delta modulator 226 may include several input capacitors andfeedback capacitors to allow for scaling over a wide array of dynamicranges of the analog-to-digital converter 160.

FIG. 4 is a flowchart illustrating one example method 400 of scaling adynamic range of the analog-to-digital converter 160. For simplicity,the method 400 is described with respect to two states: (i) a firstdynamic range (that is, a high dynamic range); and (ii) a second dynamicrange (that is, a low dynamic range). As illustrated in FIG. 4, themethod 400 includes causing the analog-to-digital converter 160 tooperate at the first dynamic range (at block 410). Because the mobilecommunications device 100 is not aware of the signal strength availableat a startup, it may be advantageous to set the analog-to-digitalconverter 160 to operate at a high dynamic range. That is, a defaultconfiguration of the analog-to-digital converter 160 is a high dynamicrange. Operating the analog-to-digital converter 160 at a high dynamicrange includes switching in, using the sample rate and bandwidthcontroller 234, capacitors having higher capacitance values (that is,the first capacitor) into the sigma-delta modulator 226. When capacitorswith higher capacitance are used in the sigma-delta modulator 226, thesigma-delta modulator 226 has higher signal-to-noise ratio and lowerintegration noise. In addition, operating the analog-to-digitalconverter 160 at a high dynamic range may also include increasing thereference voltage and sample rate of the sigma-delta modulator 226. Inaddition, the automatic gain control state machine 238 may adjust thegain of the receiver portion 200 such that the attenuation level of areceived radio frequency level is in proportion to the first dynamicrange. When the analog-to-digital converter 160 operates at a higherdynamic range, the receiver portion 200 or the antenna 140 of the mobilecommunications device 100 has higher sensitivity. In some embodiments,the automatic gain control state machine 238 may increase the biascurrent applied to the amplifiers 208, 214, 220, 224 (for example, anamplifier) when larger capacitors (for example, the first capacitor) areused in the sigma-delta modulator 226. In other words, when the firstcapacitor is switched in to the sigma-delta modulator 226, the automaticgain control state machine 238 adjusts the bias current of the amplifier208, 214, 220, 224 in proportion to the first capacitance value.

The method 400 also includes receiving the radio frequency signal at theantenna 140 (at block 420). As described above, the radio frequencysignal is received at the antenna 140 and split into an in-phasecomponent and a quadrature component. The in-phase and quadraturecomponents are then provided to the sigma-delta modulator 226.

The method 400 further includes detecting an on-channel signal level ofthe received radio frequency signal (at block 430). As described above,the on-channel detector 230 connected to the sigma-delta modulator 226receives the on-channel signal of the radio frequency signal anddetermines a power level, quality or the like of the on-channel signal.In some embodiments, the analog-to-digital converter 160 may also detectan off-channel signal profile of the radio frequency signal. Asdescribed above, an off-channel detector 216 receives the radiofrequency signal and determines the off-channel signal profile such as apower level, frequency range, and the like of the off-channel signal. Insome embodiments, the off-channel detector 216 may also estimate apeak-to-average power ratio of the off-channel signal and may correlatethe peak-to-average power ratio to the dynamic range of theanalog-to-digital converter 160.

The method 400 also includes determining whether the on-channel signallevel is above an on-channel threshold (at block 440). The receiverelectronic processor generates a scaled threshold (that is, theon-channel threshold) and determines whether the on-channel signal levelis above or below the on-channel threshold. As described above, in someembodiments, the automatic gain control threshold set block 236 maygenerate a plurality of thresholds and may compare the on-channel signallevel to the plurality of thresholds.

The method 400 also includes when the receiver electronic processordetermines that the on-channel signal level is above the on-channelthreshold, operating the analog-to-digital converter 160 at the seconddynamic range (at block 450). For example, when the receiver electronicprocessor determines that the on-channel signal is strong, theanalog-to-digital converter 160 operates at a lower dynamic range toconserve battery life of the mobile communications device 100. Operatingthe analog-to-digital converter 160 at a second dynamic range mayinclude switching in the second input capacitor 320 and/or the secondfeedback capacitor 350 (for example, second capacitor) in thesigma-delta modulator 226. As described above, the sample rate andbandwidth controller 234 may control the switching between the firstcapacitor and the second capacitor. In addition, operating theanalog-to-digital converter 160 at the second dynamic range may includereducing the sample rate and reducing the reference voltage of thesigma-delta modulator 226. The automatic gain control state machine 238automatically adjusts the gain of the receiver portion 200 based on thedetected on-channel signal level. For example, the automatic gaincontrol state machine 238 may reduce the gain when a strong on-channelsignal is detected. In addition, the automatic gain control statemachine 238 may adjust other parameters such as the stochasticresonance, current supplied to the analog-to-digital converter 160 andthe like to match the detected on-channel signal level. In someembodiments, the automatic gain control state machine 238 may reduce thebias current applied to the amplifiers 208, 214, 220, 224 (for example,an amplifier) when smaller capacitors (for example, the secondcapacitor) are used in the sigma-delta modulator 226 to reduce powerdissipation. In other words, when the second capacitor is switched in tothe sigma-delta modulator 226, the automatic gain control state machine238 adjusts the bias current of the amplifier 208, 214, 220, 224 inproportion to the second capacitance value.

The method 400 also includes when the receiver electronic processordetermines that the on-channel signal level is below the on-channelthreshold, causing the analog-to-digital converter 160 to operate at thefirst dynamic range (at block 460). For example, when the receiverelectronic processor determines that the on-channel signal is weak, theanalog-to-digital converter 160 is operated at a higher dynamic range.Operating the analog-to-digital converter 160 at the first dynamic rangemay include switching in the first input capacitor 310 and/or the firstfeedback capacitor 340 (for example, first capacitor) in the sigma-deltamodulator 226. In some embodiments, the switching operation is performedby the electronic processor 110. In addition, operating theanalog-to-digital converter 160 at the first dynamic range may includeincreasing the sample rate and increasing the reference voltage of thesigma-delta modulator 226. The automatic gain control state machine 238may adjust the on-channel automatic gain control threshold based on thedetected on-channel signal level. For example, the automatic gaincontrol state machine 238 may increase the gain thresholds when a weakon-channel signal is detected. In addition, the automatic gain controlstate machine 238 may adjust other parameters such as the stochasticresonance, current supplied to the analog-to-digital converter 160 andthe like to match the detected on-channel signal level.

The method 400 continuously adjusts the dynamic range of theanalog-to-digital converter 160 to improve the reception and batterylife of the mobile communications device 100. In some embodiments,switching between a high dynamic range and a low dynamic range induces aswitching transient noise in a call of the mobile communications device100. As a consequence, the method 400 may adjust the dynamic range ofthe analog-to-digital converter 160 during “off-slot” period or duringperiod of silence when the speaker of the mobile communications device100 is muted. In some embodiments, the method 400 detects that theon-channel signal is weak and that the off-channel interference is high.That is, the off-channel detector 216 may detect a strong undesiredoff-channel signal. The off-channel detector 216 may provide a signalprofile or signal level of the undesired off-channel signal to the RFsignal scaling and spur estimator 232. In these situations, the method400 operates the analog-to-digital converter 160 at a low dynamic rangeto conserve battery life rather than at a high dynamic range. In theseembodiments, the method 400 may operate the analog-to-digital converter160 similar to the operation based on the on-channel signal level. Thatis, the method 400 compares the off-channel signal level to anoff-channel signal threshold and adjusts the dynamic range of theanalog-to-digital converter 160 based on the comparison. However, theoff-channel signal threshold may be significantly higher than theon-channel signal threshold. The automatic gain control state machine238 may adjust other parameters accordingly. In some embodiments, the RFsignal scaling and spur estimator 232 may process signals from theon-channel detector 230 and/or the off-channel detector 216 in tandem orindividually depending on the specific signal level indication provided.Other techniques may also be used in adjusting the dynamic range of theanalog-to-digital converter 160 based on the on-channel signal level andthe off-channel signal profile. In some embodiments, the on-channelsignal level history and the off-channel signal profile history arestored on the memory 120.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings.

The benefits, advantages, solutions to problems, and any element(s) thatmay cause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeatures or elements of any or all the claims. The invention is definedsolely by the appended claims including any amendments made during thependency of this application and all equivalents of those claims asissued.

Moreover in this document, relational terms such as first and second,top and bottom, and the like may be used solely to distinguish oneentity or action from another entity or action without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions. The terms “comprises,” “comprising,” “has,”“having,” “includes,” “including,” “contains,” “containing” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises, has,includes, contains a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus. An element proceeded by“comprises . . . a,” “has . . . a,” “includes . . . a,” or “contains . .. a” does not, without more constraints, preclude the existence ofadditional identical elements in the process, method, article, orapparatus that comprises, has, includes, contains the element. The terms“a” and “an” are defined as one or more unless explicitly statedotherwise herein. The terms “substantially,” “essentially,”“approximately,” “about” or any other version thereof, are defined asbeing close to as understood by one of ordinary skill in the art, and inone non-limiting embodiment the term is defined to be within 10%, inanother embodiment within 5%, in another embodiment within 1% and inanother embodiment within 0.5%. The term “coupled” as used herein isdefined as connected, although not necessarily directly and notnecessarily mechanically. A device or structure that is “configured” ina certain way is configured in at least that way, but may also beconfigured in ways that are not listed.

It will be appreciated that some embodiments may be comprised of one ormore generic or specialized processors (or “processing devices”) such asmicroprocessors, digital signal processors, customized processors andfield programmable gate arrays (FPGAs) and unique stored programinstructions (including both software and firmware) that control the oneor more processors to implement, in conjunction with certainnon-processor circuits, some, most, or all of the functions of themethod and/or apparatus described herein. Alternatively, some or allfunctions could be implemented by a state machine that has no storedprogram instructions, or in one or more application specific integratedcircuits (ASICs), in which each function or some combinations of certainof the functions are implemented as custom logic. Of course, acombination of the two approaches could be used.

Moreover, an embodiment can be implemented as a computer-readablestorage medium having computer readable code stored thereon forprogramming a computer (e.g., comprising a processor) to perform amethod as described and claimed herein. Examples of suchcomputer-readable storage mediums include, but are not limited to, ahard disk, a CD-ROM, an optical storage device, a magnetic storagedevice, a ROM (Read Only Memory), a PROM (Programmable Read OnlyMemory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM(Electrically Erasable Programmable Read Only Memory) and a Flashmemory. Further, it is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choicesmotivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein will be readily capable of generating such softwareinstructions and programs and ICs with minimal experimentation.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed embodiment. Thus the following claims arehereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

We claim:
 1. A scalable dynamic range analog-to-digital convertercomprising: a switched capacitor sigma-delta modulator including: afirst capacitor having a first capacitance value, and a second capacitorhaving a second capacitance value; and a receiver electronic processorthat controls a switching operation of the switched capacitorsigma-delta modulator; wherein the receiver electronic processorreceives an on-channel signal level of an on-channel signal; wherein thereceiver electronic processor switches in the first capacitor when theon-channel signal level is below an on-channel threshold, and whereinthe receiver electronic processor switches in the second capacitor whenthe on-channel signal level is above the on-channel threshold.
 2. Thescalable dynamic range analog-to-digital converter of claim 1, whereinthe receiver electronic processor receives an off-channel signal profileand wherein switching between the first capacitor and the secondcapacitor is further based on the off-channel signal profile.
 3. Thescalable dynamic range analog-to-digital converter of claim 1, whereinthe first capacitance value is higher than the second capacitance value.4. A mobile communications device, comprising: an internal antenna toreceive a radio frequency (RF) signal; an on-channel detector coupled tothe internal antenna, the on-channel detector configured to detect anon-channel signal level of the radio frequency signal; ananalog-to-digital converter coupled to the internal antenna to convertthe radio frequency signal to a digital signal and including a switchedcapacitor sigma-delta modulator including: a first capacitor having afirst capacitance value; and a second capacitor having a secondcapacitance value; and a receiver electronic processor that controls aswitching operation of the switched capacitor sigma-delta modulator;wherein the receiver electronic processor switches in the firstcapacitor when the on-channel signal level is below an on-channelthreshold, and wherein the receiver electronic processor switches in thesecond capacitor when the on-channel signal level is above theon-channel threshold.
 5. The mobile communications device of claim 4,further comprising: an off-channel detector that detects an off-channelsignal profile of the radio frequency signal, wherein switching betweenthe first capacitor and the second capacitor is further based on theoff-channel signal profile.
 6. The mobile communications device of claim5, further comprising a memory coupled to the receiver electronicprocessor and configured to store an on-channel signal level history andan off-channel signal profile history.
 7. The mobile communicationsdevice of claim 4, wherein the first capacitance value is higher thanthe second capacitance value.
 8. The mobile communications device ofclaim 4, further comprising an automatic gain control state machineconfigured to: determine whether at least one of the first capacitor andthe second capacitor is switched in to the sigma-delta modulator; whenthe first capacitor is switched in to the sigma-delta modulator, adjusta gain of the analog-to-digital converter in proportion to the firstcapacitance value; and when the second capacitor is switched in to thesigma-delta modulator, adjust the gain of the analog-to-digitalconverter in proportion to the second capacitance value.
 9. The mobilecommunications device of claim 8, further comprising: an amplifiercoupled between the internal antenna and the analog-to-digitalconverter; and wherein the automatic gain control state machine isfurther configured to: when the first capacitor is switched in to thesigma-delta modulator, adjust a bias current of the amplifier inproportion to the first capacitance value; and when the second capacitoris switched in to the sigma-delta modulator, adjust the bias current ofthe amplifier in proportion to the second capacitance value.
 10. Amethod of scaling a dynamic range of an analog-to-digital converter, themethod comprising: operating the analog-to-digital converter at a firstdynamic range; receiving a radio frequency signal; detecting anon-channel signal level of the radio frequency signal; when theon-channel signal level is above an on-channel threshold, operating theanalog-to-digital converter at a second dynamic range; and when theon-channel signal level is below the on-channel threshold, operating theanalog-to-digital converter at the first dynamic range.
 11. The methodof claim 10, wherein operating the analog-to-digital converter at thefirst dynamic range comprises switching in a first capacitor of asigma-delta modulator of the analog-to-digital converter having a firstcapacitance value, and operating the analog-to-digital converter at thesecond dynamic range comprises switching in a second capacitor of thesigma-delta modulator having a second capacitance value.
 12. The methodof claim 11, wherein the first capacitance value is higher than thesecond capacitance value.
 13. The method of claim 11, further comprisingdetecting an off-channel signal profile of the radio frequency signal,wherein operating the analog-to-digital converter at the first dynamicrange and the second dynamic range is further based on the off-channelsignal profile.
 14. The method of claim 13, further comprising adjustinga gain of the analog-to-digital converter based on the on-channel signallevel and the off-channel signal profile.
 15. The method of claim 14,wherein switching between the first dynamic range and the second dynamicrange is performed during an off-slot period.
 16. The method of claim10, wherein operating the analog-to-digital converter at the firstdynamic range and the second dynamic range includes adjusting areference voltage of a sigma-delta modulator of the analog-to-digitalconverter.
 17. The method of claim 10, wherein operating theanalog-to-digital converter at the first dynamic range and the seconddynamic range includes adjusting a sample rate of a sigma-deltamodulator of the analog-to-digital converter.
 18. The method of claim10, wherein operating the analog-to-digital converter at the firstdynamic range and the second dynamic range includes adjusting a biascurrent of an amplifier coupled to the analog-to-digital converter.